/*
 * Copyright 2016, gRPC Authors All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package io.grpc.grpclb;

import io.grpc.Attributes;
import io.grpc.ExperimentalApi;
import io.grpc.Metadata;

/**
 * Constants for the GRPCLB load-balancer.
 */
@ExperimentalApi("https://github.com/grpc/grpc-java/issues/1782")
public final class GrpclbConstants {
  /**
   * The load-balancing policy designated by the naming system.
   */
  public enum LbPolicy {
    PICK_FIRST,
    ROUND_ROBIN,
    GRPCLB
  }

  /**
   * An attribute of a name resolution result, designating the LB policy.
   */
  public static final Attributes.Key<LbPolicy> ATTR_LB_POLICY =
      Attributes.Key.of("io.grpc.grpclb.lbPolicy");

  /**
   * The naming authority of an LB server address.  It is an address-group-level attribute, present
   * when the address group is a LoadBalancer.
   */
  public static final Attributes.Key<String> ATTR_LB_ADDR_AUTHORITY =
      Attributes.Key.of("io.grpc.grpclb.lbAddrAuthority");

  /**
   * The opaque token given by the remote balancer for each returned server address.  The client
   * will send this token with any requests sent to the associated server.
   */
  public static final Metadata.Key<String> TOKEN_METADATA_KEY =
      Metadata.Key.of("lb-token", Metadata.ASCII_STRING_MARSHALLER);

  private GrpclbConstants() { }
}
